Method for manufacturing solid-state imaging element, solid-state imaging element, method for manufacturing electronic apparatus, and electronic apparatus

ABSTRACT

Disclosed herein is a method for manufacturing a solid-state imaging element, the method including forming lenses that are each provided corresponding to a light receiving part of a respective one of a plurality of pixels arranged in an imaging area over a semiconductor substrate and collect light onto the light receiving parts; forming a light blocking layer by performing film deposition on the lenses by using a material having light blocking capability; and forming a light blocker composed of the material having light blocking capability at a boundary part between the lenses adjacent to each other by etching the light blocking layer in such a manner that the material having light blocking capability is left at the boundary part between the lenses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 13/480,959filed May 25, 2012, which contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2011-142428 filedin the Japan Patent Office on Jun. 28, 2011, the entire contents of bothof which are incorporated herein by reference.

BACKGROUND

The present technique relates to a method for manufacturing asolid-state imaging element, a solid-state imaging element, a method formanufacturing electronic apparatus including it, and electronicapparatus.

The solid-state imaging element typified by element of the chargecoupled device (CCD) type and element of the complementary metal oxidesemiconductor (CMOS) type includes plural pixels disposed in a matrixmanner for example and includes color filters and lenses providedcorresponding to the respective pixels.

Each pixel configuring the solid-state imaging element has a lightreceiving part such as a photodiode having a photoelectric conversionfunction. The color filters provided corresponding to the respectivepixels are each a filter part of any color among e.g. red, green, andblue and each transmit light of a component of a respective one of thecolors. The lenses provided corresponding to the respective pixels areeach provided corresponding to the light receiving part of a respectiveone of the pixels and each collect incident light from the external ontothe corresponding light receiving part. Examples of the lens included inthe solid-state imaging element include an on-chip lens provided on theupper side of the color filter (light incident side) and an in-layerlens that is provided inside the layer-laminated structure configuringthe respective pixels and collects light transmitted through the colorfilter.

In such a solid-state imaging element, a phenomenon of so-called colorcrosstalk often occurs. The color crosstalk refers to a phenomenon inwhich, at the boundary part between adjacent pixels of colors differentfrom each other, part of light incident on the color filtercorresponding to the pixel of one of the colors is incident on thephotodiode of the pixel of the other of the colors as oblique light orthe like. The color crosstalk often causes unevenness of the sensitivityand image quality in the solid-state imaging element. Problems due tosuch color crosstalk become more pronounced along withmicrominiaturization, increase in the number of pixels, and so forth inthe solid-state imaging element.

In order to suppress the color crosstalk in the solid-state imagingelement, in a related art, a light blocker as a layer or a film having alight blocking function is provided between pixels adjacent to eachother. For example, Japanese Patent Laid-open No. 10-163462(hereinafter, Patent Document 1) discloses a configuration including ametal thin film as a light blocker formed into a grid form in a latticemanner for each unit cell compartment in a solid-state imaging element.

In the configuration disclosed in Patent Document 1, each inside part ofthe grid-form metal thin film serves as a segmentalized light receivingpart region and a color filter and a microlens are independentlyprovided for each light receiving part region. The grid-form metal thinfilm exists at the boundary part between adjacent pixels, of the colorfilters and the microlenses provided corresponding to the respectivepixels.

SUMMARY

Certainly, it will be considered that, according to the configurationincluding the grid-form metal thin film surrounding each light receivingpart region in a solid-state imaging element like the configuration ofPatent Document 1, each light receiving part region is surrounded in acylindrical manner by the metal thin film and the light collectionefficiency is enhanced to allow achievement of enhancement in thesensitivity and suppression of color crosstalk.

However, in the related-art solid-state imaging element like thatdisclosed in Patent Document 1, the light blocker provided betweenadjacent pixels is formed by patterning. Therefore, pattern misalignmentbetween the lens provided corresponding to the light receiving part ofthe pixel and the light blocker located between adjacent pixels easilyoccurs and the accuracy of pattern alignment between the lens and thelight blocker is low. Unless the accuracy of pattern alignment betweenthe lens and the light blocker is sufficiently ensured, it is difficultto respond to microminiaturization and increase in the number of pixelsin the solid-state imaging element.

There is a need for the present technique to provide a method formanufacturing a solid-state imaging element, a solid-state imagingelement, a method for manufacturing electronic apparatus, and electronicapparatus that each have the following advantages. Specifically, inproviding a light blocker at the boundary part between lenses providedcorresponding to the light receiving parts of the respective pixels, thelight blocker can be formed in a self-aligned manner. Thus, the accuracyof pattern alignment between the lens and the light blocker can beenhanced and it is possible to easily respond to microminiaturizationand increase in the number of pixels.

According to an embodiment of the present technique, there is provided amethod for manufacturing a solid-state imaging element. The methodincludes forming lenses that are each provided corresponding to a lightreceiving part of a respective one of a plurality of pixels arranged inan imaging area over a semiconductor substrate and collect light ontothe light receiving parts, and forming a light blocking layer byperforming film deposition on the lenses by using a material havinglight blocking capability. The method further includes forming a lightblocker composed of the material having light blocking capability at aboundary part between the lenses adjacent to each other by etching thelight blocking layer in such a manner that the material having lightblocking capability is left at the boundary part between the lenses.

According to another embodiment of the present technique, there isprovided a solid-state imaging element including a plurality of pixelsconfigured to be arranged in an imaging area over a semiconductorsubstrate and each have a light receiving part that accumulates a signalcharge obtained by photoelectric conversion of incident light, and colorfilters configured to be each provided for a respective one of theplurality of pixels. The solid-state imaging element further includeslenses configured to be each provided corresponding to the lightreceiving part of the respective one of the plurality of pixels andcollect light onto the light receiving parts, and a light blockerconfigured to be provided at a boundary part between the lenses adjacentto each other and be composed of a metal.

According to another embodiment of the present technique, there isprovided a method for manufacturing electronic apparatus having asolid-state imaging element, an optical system that guides incidentlight to light receiving parts of the solid-state imaging element, adrive circuit that generates a drive signal for driving the solid-stateimaging element, and a signal processing circuit that processes anoutput signal of the solid-state imaging element. The method includes,as manufacturing the solid-state imaging element, forming lenses thatare each provided corresponding to the light receiving part of arespective one of a plurality of pixels arranged in an imaging area overa semiconductor substrate and collect light onto the light receivingparts, and forming a light blocking layer by performing film depositionon the lenses by using a material having light blocking capability. Themethod further includes forming a light blocker composed of the materialhaving light blocking capability at a boundary part between the lensesadjacent to each other by etching the light blocking layer in such amanner that the material having light blocking capability is left at theboundary part between the lenses.

According to another embodiment of the present technique, there isprovided electronic apparatus having a solid-state imaging element, anoptical system that guides incident light to light receiving parts ofthe solid-state imaging element, a drive circuit that generates a drivesignal for driving the solid-state imaging element, and a signalprocessing circuit that processes an output signal of the solid-stateimaging element. The solid-state imaging element includes a plurality ofpixels configured to be arranged in an imaging area over a semiconductorsubstrate and each have the light receiving part that accumulates asignal charge obtained by photoelectric conversion of incident light,and color filters configured to be each provided for a respective one ofthe plurality of pixels. The solid-state imaging element furtherincludes lenses configured to be each provided corresponding to thelight receiving part of the respective one of the plurality of pixelsand collect light onto the light receiving parts, and a light blockerconfigured to be provided at a boundary part between the lenses adjacentto each other and be composed of a metal.

According to the embodiments of the present technique, the light blockercan be formed in a self-aligned manner in providing the light blocker atthe boundary part between the lenses provided corresponding to the lightreceiving parts of the respective pixels. Thus, the accuracy of patternalignment between the lens and the light blocker can be enhanced and itis possible to easily respond to microminiaturization and increase inthe number of pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of a solid-state imagingelement according to one embodiment of the present technique;

FIG. 2 is a sectional view showing the configuration of the solid-stateimaging element according to one embodiment of the present technique;

FIG. 3 is an explanatory diagram about effects of the solid-stateimaging element according to one embodiment of the present technique;

FIG. 4 is a diagram showing one example of a simulation result of thesolid-state imaging element according to one embodiment of the presenttechnique;

FIG. 5 is a sectional view showing a modification example of thesolid-state imaging element according to one embodiment of the presenttechnique;

FIGS. 6A to 6C are explanatory diagrams about a method for manufacturingthe solid-state imaging element according to one embodiment of thepresent technique;

FIGS. 7A to 7C are explanatory diagrams about a modification example ofthe method for manufacturing the solid-state imaging element accordingto one embodiment of the present technique;

FIGS. 8A to 8C are explanatory diagrams about a modification example ofthe method for manufacturing the solid-state imaging element accordingto one embodiment of the present technique;

FIG. 9 is an explanatory diagram about a modification example of themethod for manufacturing the solid-state imaging element according toone embodiment of the present technique;

FIGS. 10A and 10B are explanatory diagrams about a modification exampleof the method for manufacturing the solid-state imaging elementaccording to one embodiment of the present technique;

FIGS. 11A to 11D are explanatory diagrams about a method formanufacturing the solid-state imaging element according to a secondembodiment of the present technique;

FIGS. 12A to 12E are explanatory diagrams about a method formanufacturing the solid-state imaging element according to a thirdembodiment of the present technique;

FIGS. 13A to 13E are explanatory diagrams about a method formanufacturing the solid-state imaging element according to a fourthembodiment of the present technique;

FIGS. 14A to 14E are explanatory diagrams about a method formanufacturing the solid-state imaging element according to a fifthembodiment of the present technique; and

FIG. 15 is a diagram showing the configuration of electronic apparatusaccording to one embodiment of the present technique.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[Outline of Present Technique]

Because of recent requirements for the solid-state imaging element tohave smaller size and a larger number of pixels, the incident angle oflight to the end of angle of view of the solid-state imaging elementbecomes increasingly larger. Light having a large incident angle causescolor crosstalk between pixels as obliquely incident light. So, forsuppression of the color crosstalk worsened due to obliquely incidentlight, it is effective to provide a light blocker at the boundary partbetween pixels, of lenses provided corresponding to light receivingparts of the respective pixels, specifically e.g. at the bottom of thegap part between the lenses. However, if the accuracy of patternalignment between the lens and the light blocker is low, it is difficultto respond to microminiaturization and increase in the number of pixelsin the solid-state imaging element and the lowering of the sensitivityoccurs in some cases.

An embodiment of the present technique provides a light blocker at theboundary part between lenses provided corresponding to light receivingparts of the respective pixels to thereby reduce color crosstalk andallows the light blocker between the lenses to be formed in aself-aligned manner. This enhances the accuracy of pattern alignmentbetween the lens and the light blocker and makes it easy to respond tomicrominiaturization and increase in the number of pixels in thesolid-state imaging element.

Furthermore, an embodiment of the present technique uses a metal as thematerial of the light blocker provided between the lenses adjacent toeach other to thereby realize a solid-state imaging element that canwithstand a high temperature process and has a wide application rangewith achievement of high light blocking capability regarding the lightblocker.

Embodiments of the present technique will be described below. Theembodiments to be described below will be explained by taking asolid-state imaging element (image sensor) of a CCD type as an exampleof a solid-state imaging element. However, embodiments of the presenttechnique can be widely applied also to other solid-state imagingelements such as a solid-state imaging element of a CMOS type, besidesthe CCD-type element.

[Configuration of Solid-State Imaging Element]

The configuration of a solid-state imaging element according to a firstembodiment of the present technique will be described with use of FIG. 1and FIG. 2. FIG. 2 is equivalent to a partial sectional view at positionA-A′ in FIG. 1.

As shown in FIG. 1 and FIG. 2, a solid-state imaging element 1 has arectangular imaging area 2 configured over a semiconductor substrate 11.The solid-state imaging element 1 includes plural light receiving parts3 in the imaging area 2. The plural light receiving parts 3 are arrangedin a matrix manner in the imaging area 2 over the semiconductorsubstrate 11. Specifically, the plural light receiving parts 3 aredisposed in a two-dimensional matrix manner in the longitudinaldirection and the lateral direction along the rectangular imaging area2. For the solid-state imaging element 1 of the present embodiment, thelongitudinal direction is defined as the vertical direction and thelateral direction is defined as the horizontal direction in FIG. 1.

The light receiving part 3 is configured by a photodiode 17, which is aphotoelectric conversion element, and configures a pixel 7 in theimaging area 2. That is, the plural pixels 7 included in the solid-stateimaging element 1 are arranged in the imaging area 2 over thesemiconductor substrate 11 and each have the light receiving part 3. Thelight receiving part 3 accumulates a signal charge obtained byphotoelectric conversion of incident light. Specifically, the lightreceiving part 3 has a light receiving surface and generates a signalcharge depending on the amount (intensity) of light incident on thelight receiving surface by photoelectric conversion to accumulate thegenerated signal charge.

The solid-state imaging element 1 includes plural vertical transferregisters 4 that transfer the signal charge in the vertical directionand a horizontal transfer register 5 that transfers, in the horizontaldirection, the signal charge transferred by the vertical transferregisters 4 as charge transfer sections (transfer registers) thattransfer the signal charge generated by the light receiving parts 3.

The vertical transfer registers 4 are provided along the respectivelines of the column direction (vertical direction) in thetwo-dimensional matrix arrangement of the plural light receiving parts3. Specifically, as shown in FIG. 1, the plural vertical transferregisters 4 are provided in such a state as to be each adjacent to oneside (left side, in FIG. 1) of a respective one of the columns and bedisposed in parallel to each other along the lines of the lightreceiving parts 3 in the vertical direction, for each of the columns ofthe plural light receiving parts 3 disposed in a matrix manner in thevertical direction. The signal charge generated by the light receivingpart 3 is read out to the vertical transfer register 4 and transferredin the vertical direction by the vertical transfer register 4.

The horizontal transfer register 5 is disposed along the side of therectangular imaging area 2 along the horizontal direction on one side inthe vertical direction (lower side, in FIG. 1). Therefore, the verticaltransfer register 4 transfers the signal charge read out from the lightreceiving part 3 in the vertical direction toward the horizontaltransfer register 5 (toward the lower side, in FIG. 1).

The signal charge transferred by the vertical transfer register 4 andthe horizontal transfer register 5 is output from an output section 6provided on the termination side of the horizontal transfer register 5.The output section 6 converts the transferred signal charge to anelectrical signal by an output amplifier such as a floating diffusion(FD) amplifier and outputs it.

The vertical transfer register 4 and the horizontal transfer register 5each have plural kinds of electrodes and a buried transfer regionprovided on the lower side of the electrodes (on the side of thesemiconductor substrate 11). In FIG. 2, transfer electrodes 12 as theelectrodes configuring the vertical transfer registers 4 are shown.

The vertical transfer register 4 and the horizontal transfer register 5are each driven by plural-phase drive pulses. The vertical transferregister 4 is driven by e.g. four-phase drive pulses. In this case, thevertical transfer register 4 has four kinds of transfer electrodesassociated with the four-phase driving as the transfer electrodes 12.These four kinds of transfer electrodes include a read electrode forreading out the signal charge from the light receiving part 3. In thevertical transfer register 4, these four kinds of transfer electrodesare repeatedly provided in predetermined order in the vertical directionin units of two pixels 7 adjacent to each other in the verticaldirection (in units of two pixels).

These four kinds of transfer electrodes included in the verticaltransfer register 4 are each independently given a respective one offour-phase clock pulses Vφ1, Vφ2, Vφ3, and Vφ4 as a drive voltage. Byproper control of the amplitude and timing of these four-phase clockpulses Vφ1, Vφ2, Vφ3, and Vφ4, the signal charge read out from therespective light receiving parts 3 to the vertical transfer register 4is transferred in accordance with the sequence of the electrodes of thevertical transfer register 4.

The horizontal transfer register 5 is driven by e.g. three-phase drivepulses. In this case, the horizontal transfer register 5 has three kindsof transfer electrodes associated with the three-phase driving as theelectrodes. These three kinds of transfer electrodes included in thehorizontal transfer register 5 are each independently given a respectiveone of three-phase clock pulses Hφ1, Hφ2, and Hφ3 as a drive voltage. Byproper control of the amplitude and timing of these three-phase clockpulses Hφ1, Hφ2, and Hφ3, the signal charge transferred from thevertical transfer register 4 to the horizontal transfer register 5 istransferred in the horizontal direction.

The sectional structure of the solid-state imaging element 1 will bedescribed. As shown in FIG. 2, over the transfer electrode 12 of thevertical transfer register 4, a connection line 14 is provided with theintermediary of an insulating film 13 that is e.g. a silicon oxide film(SiO₂ film). The connection line 14 is electrically connected to thetransfer electrode 12 via a contact 15 composed of e.g. tungsten. Theconnection line 14 is disposed in association with the arrangement ofvarious kinds of transfer electrodes 12 on a predetermined route alongthe horizontal direction and the vertical direction, and functions toapply predetermined drive voltages to the respective transfer electrodes12.

As shown in FIG. 2, a semiconductor layer 16 is provided on thesemiconductor substrate 11 and the photodiode 17 configuring the lightreceiving part 3 is provided in this semiconductor layer 16. If thesemiconductor substrate 11 is a silicon semiconductor substrate of then-type as a first conductivity type for example, the semiconductor layer16 is formed as a semiconductor well region of the p-type as a secondconductivity type.

On the semiconductor layer 16, a gate oxide film 18 is provided underthe transfer electrode 12 of the vertical transfer register 4. That is,over the semiconductor layer 16, the transfer electrode 12 is providedwith the intermediary of the gate oxide film 18 and the connection line14 is provided over the transfer electrode 12 with the intermediary ofthe insulating film 13. The insulating film 13 is so provided as tocover the transfer electrodes 12 and part including the areas where theconnection line 14 provided over the transfer electrode 12 is disposedand the areas where the light receiving parts 3 are disposed.

On the insulating film 13, light blocking films 19 are so provided as tocover the transfer electrodes 12 of the vertical transfer registers 4and the connection line 4 in the areas outside the areas where the lightreceiving parts 3 are provided. Over the light receiving part 3, part ofthe insulating film 13 exists and an insulating film 20 that is e.g. asilicon nitride film (SiN film) is provided. A multilayer insulatingfilm composed of the insulating films 13 and 20 over this lightreceiving part 3 functions as an antireflection layer at the interfaceof the semiconductor substrate 11 and prevents the lowering of thesensitivity.

In the imaging area 2, a waveguide 21 for collecting incident light ontothe light receiving parts 3 is provided on the upper side of thesemiconductor layer 16, in which the light receiving parts 3 areprovided. The waveguide 21 is composed of a clad layer 22 and a corelayer 23.

The clad layer 22 is so formed as to follow the shape of thelayer-laminated structure composed of the transfer electrode 12 of thevertical transfer register 4 provided along the arrangement of the lightreceiving parts 3, the connection line 14, and the light blocking film19 and cover this layer-laminated structure. Therefore, in the cladlayer 22, concave parts are formed between the vertical transferregisters 4 adjacent to each other.

The core layer 23 is so provided as to fill the concave parts formed inthe clad layer 22. The core layer 23 is composed of a material having arefractive index higher than that of the material of the clad layer 22.For example, if the clad layer 22 is formed by a silicon oxide film, thecore layer 23 is formed by e.g. a silicon nitride film or a siliconoxynitride film, which is a material having a refractive index higherthan that of the silicon oxide film.

In-layer lenses 30 are provided on the waveguide 21. In the presentembodiment, the in-layer lens 30 is provided corresponding to the lightreceiving part 3 (photodiode 17) configuring the pixel 7 for each pixel7. Therefore, the plural in-layer lenses 30 are disposed in a matrixmanner in the plane similarly to the pixels 7. In the presentembodiment, the in-layer lenses 30 are composed of e.g. an inorganicmaterial such as SiN (silicon nitride). In this manner, the solid-stateimaging element 1 includes the in-layer lenses 30 that are each providedcorresponding to the light receiving part 3 of a respective one of theplural pixels 7 and collect light onto the light receiving parts 3.

As shown in FIG. 2, the in-layer lens 30 has a convex shape toward thelight incident side (upper side in FIG. 2). Specifically, in the presentembodiment, the in-layer lens 30 has a sectional shape that is asubstantially elliptical shape or a substantially circular shape. Thus,the boundary part between the in-layer lenses 30 adjacent to each otherforms a concave part. In the present embodiment, at the boundary partbetween the in-layer lenses 30 adjacent to each other, a gap part 31exists and a flat part 32 linking the bottoms of the in-layer lenses 30to each other is provided. The flat part 32 is a film-like part disposedalong the top surface of the core layer 23 of the waveguide 21 betweenthe in-layer lenses 30 adjacent to each other, and is part formedcollectively with the in-layer lenses 30.

A passivation film 24 is provided on the in-layer lenses 30. Thepassivation film 24 is so formed as to cover the whole surface of thein-layer lenses 30, including the flat parts 32. The passivation film 24is formed by e.g. a silicon oxide film (SiO₂). A color filter layer 26is provided over the passivation film 24 with the intermediary of aplanarization film 25. The planarization film 25 is formed by e.g. anorganic applied film of an acrylic resin or the like. The passivationfilm 24 may be omitted and the planarization film 25 may be provided onthe in-layer lenses 30. In this case, the planarization film 25 is soformed as to cover the whole surface of the in-layer lenses 30,including the flat parts 32.

The color filter layer 26 is divided into color filters 27 providedcorresponding to the respective pixels 7. That is, the color filterlayer 26 is divided into the plural color filters 27 for each lightreceiving part 3 (photodiode 17) configuring a respective one of thepixels 7. In the solid-state imaging element 1 of the presentembodiment, each color filter 27 is a filter part of any color among red(R), green (G), and blue (B) and transmits light of a component of arespective one of the colors. The color filters 27 of the respectivecolors are so-called on-chip color filters and are formed in accordancewith the arrangement of the plural pixels 7. In this manner, thesolid-state imaging element 1 includes the color filters 27 eachprovided for a respective one of the plural pixels 7.

Plural microlenses 35 are provided on the color filter layer 26. Themicrolens 35 is a so-called on-chip microlens and is formed for eachpixel 7 corresponding to the light receiving part 3 (photodiode 17)configuring the pixel 7. Therefore, the plural microlenses 35 aredisposed in a matrix manner in the plane similarly to the pixels 7. Inthe present embodiment, the microlenses 35 are composed of e.g. aninorganic material such as SiN (silicon nitride). In this manner, thesolid-state imaging element 1 includes the microlenses 35 that are eachprovided corresponding to the light receiving part 3 of a respective oneof the plural pixels 7 and collect light onto the light receiving parts3.

As shown in FIG. 2, the microlens 35 has a convex shape toward the lightincident side (upper side in FIG. 2). Thus, the boundary part betweenthe microlenses 35 adjacent to each other forms a concave part.

The microlens 35 collects incident light from the external onto thelight receiving part 3 (photodiode 17) of the corresponding pixel 7. Thelight focused by the microlens 35 is further collected by the in-layerlens 30 provided on the waveguide 21 as described above to be guided tothe light receiving part 3.

In this manner, the solid-state imaging element 1 of the presentembodiment has the microlenses 35, which are on-chip lenses provided onthe color filter 27, and the in-layer lenses 30 provided inside thelayer-laminated structure configuring the respective pixels 7 as lensesthat are each provided corresponding to the light receiving part 3 of arespective one of the plural pixels 7 and collect light onto the lightreceiving parts 3. Due to this feature, high efficiency of lightcollection onto the light receiving part 3 is obtained and favorablesensitivity is achieved.

In the solid-state imaging element 1 of the present embodiment havingthe above-described configuration, light blockers 40 are each providedat the boundary part between the in-layer lenses 30 adjacent to eachother. The light blocker 40 is provided as a layer-like or film-likepart stacked on the flat part 32 between the lenses of the in-layerlenses 30 adjacent to each other. That is, the light blocker 40 isprovided at the bottom of the gap part 31 between the lenses of thein-layer lenses 30.

The light blocker 40 is formed by using a metal as its material. As themetal to form the light blocker 40, e.g. any one kind of W (tungsten),Al (aluminum), Ag (silver), Au (gold), Ru (ruthenium), Ti (titanium),etc. or an alloy containing at least two kinds of metals among thesemetals is used.

By providing the light blocker 40 at the boundary part between thein-layer lenses 30 adjacent to each other in this manner, colorcrosstalk at the boundary part between the adjacent pixels 7 of colorsdifferent from each other can be reduced. The “color” about the pixel 7means the color of the color filter 27 corresponding to this pixel 7.The effect of reduction in color crosstalk by the light blocker 40 willbe described with use of FIG. 3.

In FIG. 3, as one example of the combination of the pixels 7 of colorsdifferent from each other, a combination in which a green (G) pixel 7having a green color filter 27G (hereinafter, referred to as the “Gpixel 7G”) and a red (R) pixel 7 having a red color filter 27 (27R)(hereinafter, referred to as the “R pixel 7R”) are adjacent to eachother is shown. Furthermore, in the sectional view shown in FIG. 3,hatching for part of the constituent elements is omitted forconvenience.

As shown in FIG. 3, the most part of light incident on the microlens 35of the G pixel 7G is transmitted through the green color filter 27G andenters the photodiode 17 of the G pixel 7G. Meanwhile, the lightincident on the microlens 35 of the G pixel 7G includes oblique lightthat cannot be collected by the microlens 35 and travels toward the Rpixel 7R adjacent to the G pixel 7G after being transmitted through thegreen color filter 27G to enter the photodiode 17 of this R pixel 7R(see solid arrow L1 and dashed arrow L2).

Furthermore, the most part of light incident on the microlens 35 of theR pixel 7R is transmitted through the red color filter 27R and entersthe photodiode 17 of the R pixel 7R. Therefore, if the light transmittedthrough the green color filter 27G enters the photodiode 17 of the Rpixel 7R as oblique light as described above, color crosstalk of green(G) and red (R) occurs. That is, optical color crosstalk occurs becausethe color of the color filter 27 through which light incident on thephotodiode 17 is transmitted is different from the color of the colorfilter 27 provided corresponding to the photodiode 17 that receives thislight.

So, the optical color crosstalk is suppressed due to the provision ofthe light blocker 40 at the boundary part between the in-layer lenses 30adjacent to each other like in the solid-state imaging element 1 of thepresent embodiment. Specifically, as shown in FIG. 3, for example, theoblique light that is not collected by the microlens 35 and travelstoward the R pixel 7R adjacent to the G pixel 7G (solid arrow L1), ofthe light incident on the microlens 35 of the G pixel 7G, is blocked bythe light blocker 40 existing at the boundary part between the in-layerlenses 30. That is, the light that enters the photodiode 17 of theadjacent R pixel 7R from the side of the G pixel 7G if the light blocker40 does not exist (dashed arrow L2) is incident on the light blocker 40and reflected (solid arrows L1 and L3). This prevents the oblique lightthat causes color crosstalk between different-color pixels from enteringthe photodiode 17 and thus suppresses color crosstalk.

Furthermore, the light blocker 40 provided between the lenses of thein-layer lenses 30 in the solid-state imaging element 1 of the presentembodiment is formed by a metal and thus can achieve high light blockingcapability. Specifically, as a material to form a layer having lightblocking capability, e.g. a resin material obtained by mixing carbon ina thermosetting resin will be available. However, such a resin materialhas low light blocking capability and cannot sufficiently suppress colorcrosstalk in some cases. In this regard, the light blocker 40 includedin the solid-state imaging element 1 of the present embodiment canachieve high light blocking capability and can effectively reduce colorcrosstalk because it is formed by a metal.

Furthermore, because the light blocker 40 included in the solid-stateimaging element 1 of the present embodiment is formed by a metal, highheat resistance against a high temperature process in the manufacturingprocess of the solid-state imaging element 1 can be easily obtained.Specifically, if the above-described resin material is used as thematerial of the light blocker 40, the light blocker 40 cannot withstanda high temperature process such as a step of performing reflow treatmentin forming the microlenses 35 in some cases. In this regard, the lightblocker 40 included in the solid-state imaging element 1 of the presentembodiment can achieve high heat resistance and the application rangecan be widened because it is formed by a metal.

As shown in FIG. 2, the solid-state imaging element 1 of the presentembodiment includes light blockers 45 between lenses also in themicrolenses 35, which are on-chip lenses, in addition to the lightblockers 40 provided between the lenses of the in-layer lenses 30. Thatis, in the solid-state imaging element 1 of the present embodiment, thelight blocker 45 is provided at the boundary part between themicrolenses 35 adjacent to each other.

The light blocker 45 is provided between the lenses of the microlenses35 similarly to the light blocker 40 between the lenses of the in-layerlenses 30. The microlens 35 is a so-called gapless lens having no gappart in the relationship with the adjacent microlens 35. Also in such agapless configuration, the light blocker 45 is provided at the concavepart existing at the boundary part between the microlenses 35 adjacentto each other.

The light blocker 45 is formed by using a metal as its materialsimilarly to the light blocker 40 between the lenses of the in-layerlenses 30. That is, as the metal to form the light blocker 45, e.g. anyof W (tungsten), Al (aluminum), Ag (silver), Au (gold), Ru (ruthenium),Ti (titanium), etc. or an alloy containing at least two kinds of metalsamong these metals is used.

By providing the light blocker 45 also between the lenses of themicrolenses 35 in addition to the light blocker 40 between the lenses ofthe in-layer lenses 30 in this manner, oblique light that causes colorcrosstalk between different-color pixels can be effectively preventedfrom entering the photodiode 17 and the effect of reduction in colorcrosstalk can be enhanced. Furthermore, the light blocker 45 can easilyachieve high light blocking capability and high heat resistance againsta high temperature process because it is formed by using a metalsimilarly to the light blocker 40 between the lenses of the in-layerlenses 30.

Next, one example of the result of optical simulation about thesolid-state imaging element 1 of the present embodiment will bedescribed. In the present example, as the simulation conditions, thecases in which the incident angle of green incident light transmittedthrough the green color filter 27G was 0° (vertical direction, see arrowX0) and was 10° (see arrow X1) as shown in FIG. 3 were used regardingeach of the case in which the light blocker 40 was provided between thelenses of the in-layer lenses 30 like in the solid-state imaging element1 of the present embodiment (defined as “present embodiment example”)and the case in which the light blocker 40 was not provided between thelenses of the in-layer lenses 30 (defined as “comparative example”).Furthermore, W (tungsten) was employed as the material of the lightblocker 40. Under such conditions, simulation about the respectivevalues of the color crosstalk rate (R pixel sensitivity/G pixelsensitivity [%]) and the sensitivity was performed.

FIG. 4 shows the result of this simulation. In FIG. 4, graphs G1 and G2indicated by dashed lines show the simulation result about the colorcrosstalk rate. The graph G1 shows the present embodiment example andthe graph G2 shows the comparative example. Furthermore, in FIG. 4,graphs G3 and G4 indicated by solid lines show the simulation resultabout the sensitivity. The graph G3 shows the present embodiment exampleand the graph G4 shows the comparative example.

As is understood from the graphs G1 and G2 in FIG. 4 regarding the colorcrosstalk rate, if the incident angle of the incident light is 0°, thevalue of the color crosstalk rate is substantially the same between thepresent embodiment example and the comparative example. On the otherhand, if the incident angle of the incident light is 10°, the colorcrosstalk rate greatly rises in the comparative example (graph G2)whereas the rise of the color crosstalk rate is slight in the presentembodiment example (graph G1). That is, the color crosstalk rate isdecreased by disposing the light blocker 40 between the lenses of thein-layer lenses 30. Specifically, a result that the amount of decreasein the color crosstalk rate in the present embodiment example from thecomparative example was about 2% was obtained.

As is understood from the graphs G3 and G4 in FIG. 4 regarding thesensitivity, the sensitivity of the present embodiment example (graphG3) is slightly lower than that of the comparative example (graph G4).Furthermore, in both of the present embodiment example (graph G3) andthe comparative example (graph G4), the sensitivity is lower when theincident angle of the incident light is 0° than when the incident angleis 10°. The degree of this sensitivity lowering is substantially thesame between the present embodiment example (graph G3) and thecomparative example (graph G4). That is, although the sensitivity islowered by disposing the light blocker 40 between the lenses of thein-layer lenses 30, the amount of this lowering is slight. Specifically,a result that the amount of sensitivity lowering in the presentembodiment example from the comparative example was about 1% wasobtained.

As above, by the present simulation, the result was obtained that colorcrosstalk can be reduced without causing large sensitivity lowering,i.e. with the sensitivity nearly kept, by providing the light blocker 40between the lenses of the in-layer lenses 30 like in the solid-stateimaging element 1 of the present embodiment.

MODIFICATION EXAMPLE

A modification example of the solid-state imaging element 1 of thepresent embodiment will be described with use of FIG. 5. As shown inFIG. 5, a solid-state imaging element 1A of the present example isdifferent from the solid-state imaging element 1 shown in FIG. 2 in thatit does not include the in-layer lens 30. Specifically, in thesolid-state imaging element 1A of the present example, the passivationfilm 24 is provided on the waveguide 21 and the color filter layer 26and the plural microlenses 35 are provided over the passivation film 24with the intermediary of the planarization film 25.

Furthermore, in the solid-state imaging element 1A of the presentexample, the light blocker 45 is provided at the boundary part betweenthe microlenses 35 adjacent to each other. That is, the solid-stateimaging element 1A of the present example does not have the in-layerlens and thus includes only the light blocker 45 provided at theboundary part of the microlenses 35 adjacent to each other as the lightblocker between lenses between the pixels 7 adjacent to each other.

Also by the configuration including the light blocker 45 only at theboundary part between the microlenses 35 adjacent to each other in thismanner, the above-described color crosstalk reduction effect can beachieved. It is also possible to employ a configuration including thelight blocker 40 or 45 only either one of between the lenses of thein-layer lenses 30 and between the lenses of the microlenses 35 in theconfiguration including the in-layer lenses 30 as shown in FIG. 2.

[Method for Manufacturing Solid-State Imaging Element]

As a method for manufacturing the solid-state imaging element 1according to the present embodiment, a method for forming the lightblocker 40 provided between the lenses of the in-layer lenses 30(hereinafter, referred to as the “light blocker 40 of the in-layer lens30”) and the light blocker 45 provided between the lenses of themicrolenses 35 (hereinafter, referred to as the “light blocker 45 of themicrolens 35”) will be described. The light blocker 40 of the in-layerlens 30 and the light blocker 45 of the microlens 35 can be formed by acommon method. Therefore, in the following, how to form the lightblocker 40 of the in-layer lens 30 will be mainly described.

(Forming of Lens)

In forming the light blocker 40 of the in-layer lens 30, first a step offorming the in-layer lenses 30 is carried out. As shown in FIG. 6A, inthe case of the solid-state imaging element 1 of the present embodiment,the plural in-layer lenses 30 corresponding to the light receiving parts3 of the respective pixels 7 are formed on the waveguide 21,specifically on the surface of the core layer 23 configuring thewaveguide 21.

The plural in-layer lenses 30 are formed by a method that is publiclyknown in the technical field of the solid-state imaging element, such asa reflow method. In the state in which the in-layer lenses 30 have beenformed, the gap part 31 exists at the boundary part between the in-layerlenses 30 adjacent to each other. Furthermore, the flat part 32 linkingthe bottoms of the in-layer lenses 30 to each other is formed togetherwith the in-layer lenses 30.

The in-layer lenses 30 are formed by using a material having arefractive index higher than that of the material of the layer or filmformed on the in-layer lenses 30. Specifically, when the refractiveindex of the material of the in-layer lenses 30 is defined as n1 and therefractive index of the material of the layer or film formed on thein-layer lenses 30 is defined as n2, a material satisfying arelationship of n1>n2 is used as the material of the in-layer lenses 30.This relationship of the refractive index is a condition for allowingthe in-layer lens 30 to obtain a function as an optical element thatrefracts light and collects the light onto the photodiode 17 locatedbelow the in-layer lens 30.

In the configuration in which the passivation film 24 is formed on thein-layer lenses 30 like the solid-state imaging element 1 of the presentembodiment, for example if the material of the passivation film 24 is aSiO₂ film (silicon oxide film), the in-layer lenses 30 are formed by SiN(silicon nitride). When the wavelength of light is 550 nm, therefractive index of SiO₂ (n2) is 1.4 to 1.5 and the refractive index ofSiN (n1) is a value in a range of about 1.8 to 2.1 depending on thefabrication method and so forth. If the passivation film 24 is omittedand the planarization film 25 is formed on the in-layer lenses 30 asdescribed above, the in-layer lenses 30 are formed by SiN whereas theplanarization film 25 is formed by e.g. an organic applied film of anacrylic resin. When the wavelength of light is 550 nm, the refractiveindex of the organic applied film (n2) is 1.4 to 1.5.

The material of the in-layer lens 30 is not limited to theabove-described examples and an appropriate material is employed basedon the relationship of the refractive index with the layer or filmformed on the in-layer lens 30, and so forth. Furthermore, by using anorganic material such as a resin as the material of the in-layer lens30, the refractive index can be adjusted to about 1.6 based on thefabrication method and so forth. However, in view of achievement of heatresistance against a high temperature process, it is preferable that thematerial of the in-layer lens 30 be an inorganic material such as SiN(silicon nitride).

If a low temperature oxidation (LTO) film is employed as the film formedon the in-layer lenses 30, the refractive index (n2) can be suppressedto about 1.3. Thus, the selection range of the material of the in-layerlens 30 can be widened in terms of the refractive index. Furthermore, avacuum layer may be employed as the layer formed on the in-layer lenses30. In this case, the refractive index of the vacuum layer (n2) is 1.

In the case of the microlens 35, which is an on-chip lens, themicrolenses 35 are formed corresponding to the respective color filters27 on the color filter layer 26 in the step of forming the lenses. Inthis case, the air (atmosphere) exists on the microlenses 35 andtherefore a material having a refractive index higher than that of theair is used as the material of the microlens 35.

(Film Deposition of Light Blocking Layer)

Next, a step of forming a light blocking layer on the in-layer lenses 30is carried out. Specifically, as shown in FIG. 6B, film deposition isperformed on the in-layer lenses 30 formed on the waveguide 21 by usinga material having light blocking capability (hereinafter, referred to asthe “light blocking material”) and thereby a light blocking layer 41 isformed.

In the step of forming the light blocking layer 41, the light blockingmaterial to form the light blocker 40 is so deposited as to fill the gappart 31 between the in-layer lenses 30 adjacent to each other, so thatthe light blocking layer 41 is formed. The light blocking layer 41 isdeposited by using, as the light blocking material, e.g. any one kind ofW (tungsten), Al (aluminum), Ag (silver), Au (gold), Ru (ruthenium), Ti(titanium), etc. or an alloy containing at least two kinds of metalsamong these metals. However, the light blocking material to form thelight blocking layer 41 is not limited to the metal and e.g. a resinmaterial obtained by mixing carbon in a thermosetting resin may beemployed.

The light blocking layer 41 is so formed as to totally cover the pluralin-layer lenses 30 and the flat parts 32 existing at the boundary partbetween them. Therefore, the top surface of the light blocking layer 41has e.g. a convex shape that follows the shape of the in-layer lenses30.

As the method for depositing the light blocking layer 41, e.g. asputtering method or a chemical vapor deposition (CVD) method is used.The sputtering method is preferable in that high adhesion of the lightblocking layer 41 to the in-layer lenses 30 and the flat parts 32 isobtained. The CVD method is preferable in that high filling capabilityof the metal material to form the light blocking layer 41 for the gappart 31 is obtained. So, the following method can be employed in thestep of forming the light blocking layer 41.

First, by the sputtering method, the light blocking material to form thelight blocking layer 41 is deposited on the group of the in-layer lenses30 including the flat parts 32. Thereby, high adhesion is obtained.Next, by the CVD method, the film deposition of the light blockingmaterial to form the light blocking layer 41 is continued. Thereby, thelight blocking layer 41 is formed with achievement of high fillingcapability for the gap part 31. In this case, the step of forming thelight blocking layer 41 has a first film deposition step of depositingthe light blocking material on the in-layer lenses 30 by sputtering anda second film deposition step of further depositing the light blockingmaterial on the light blocking material deposited on the in-layer lenses30 by CVD after the first step. By employing the two-stage filmdeposition method as the combination of both of sputtering method andCVD method in this manner, advantages of both can be obtained andfavorable film deposition characteristics about the light blocking layer41 are obtained.

The adhesion of the material of the light blocking layer 41 to thematerial of the in-layer lens 30 is affected by the combination of thematerial of the in-layer lens 30 and the material of the light blockinglayer 41 besides the method of the film deposition of the light blockinglayer 41. Therefore, in selection of the material of the light blockinglayer 41, the adhesion associated with the combination with the materialof the in-layer lens 30 is taken into consideration.

(Etching)

Then, by partially removing the light blocking layer 41 formed on thein-layer lenses 30 by etching, a step of forming the light blocker 40 ofthe in-layer lens 30 by the light blocking material to form the lightblocking layer 41 is carried out. Specifically, as shown in FIG. 6C, thelight blocking layer 41 is so etched that the light blocking material isleft at the boundary part between the in-layer lenses 30 adjacent toeach other. Thereby, the light blocker 40 composed of the light blockingmaterial is formed at the boundary part between the in-layer lenses 30adjacent to each other.

In this etching step, the light blocking layer 41 is partially removedin such a manner that the light blocking layer 41 with a predeterminedfilm thickness is left on the flat parts 32 between the lenses of thein-layer lenses 30 and the light blockers 40 are formed by the materialof the light blocking layer 41. At this time, the etching is soperformed that the light blocking layer 41 is not left on the in-layerlenses 30 and the in-layer lenses 30 are not removed.

To perform such selective etching, an etching condition that provideshigh etching selectivity between the material of the in-layer lens 30and the material of the light blocking layer 41 is employed. Forexample, if the material of the in-layer lens 30 is SiN (siliconnitride) and the material of the light blocking layer 41 is tungsten, anetching condition that provides high etching selectivity between SiN andtungsten is employed.

As the etching condition that provides high etching selectivity betweenthe material of the in-layer lens 30 and the material of the lightblocking layer 41, e.g. the following condition is used. As the etchinggas, a mixed gas of SF₆ (sulfur hexafluoride), Cl₂ (chlorine), O₂(oxygen), and N₂ (nitrogen) is used. The respective gases are used atthe following flow rates: 100 [ml/min] for SF₆; 50 [ml/min] for Cl₂; 10[ml/min] for O₂; and 50 [ml/min] for N₂. The pressure of the treatmentatmosphere is set to 0.5 [Pa]. The source power is set to about 1000 [W]and the bias power applied to the wafer side (side of the semiconductorsubstrate 11) is set to about 25 [W]. The temperature of the stage onwhich the etching treatment target is placed is set to about 60 [° C.].The final film thickness of the light blocker 40 is adjusted by timecontrol in the etching or end point detection. The etching methodincludes dry etching using an etching gas and wet etching as long as themethod can satisfy the etching condition that provides high etchingselectivity between the material of the in-layer lens 30 and thematerial of the light blocking layer 41, and an appropriate etchingmethod is used.

In terms of ensuring the lens function of the in-layer lens 30, it ismore preferable that the film thickness of the light blocking layer 41left on the flat part 32, i.e. the film thickness of the light blocker40, be smaller. However, the small film thickness of the light blocker40 is in a trade-off relationship with ensuring the light blockingfunction by the light blocker 40. Therefore, it is preferable tooptimally design the amount of removal of the light blocking layer 41 inthis etching step, i.e. the film thickness of the light blocking layer41 left on the flat part 32 (film thickness of the light blocker 40),for each of the materials of the in-layer lens 30 and the light blockinglayer 41 and the shape of the in-layer lens 30.

In the above-described manner, the light blocker 40 of the in-layer lens30 included in the solid-state imaging element 1 of the presentembodiment is formed. According to the method for manufacturing thesolid-state imaging element 1 in accordance with the present embodimentincluding the above-described respective steps, the light blocker 40 canbe formed in a self-aligned manner in providing the light blocker 40 atthe boundary part between the lenses of the in-layer lenses 30 providedcorresponding to the light receiving parts 3 of the respective pixels 7.Thus, the accuracy of pattern alignment between the in-layer lens 30 andthe light blocker 40 can be enhanced and it is possible to easilyrespond to microminiaturization and increase in the number of pixels.

Specifically, according to the method for manufacturing the solid-stateimaging element 1 in accordance with the present embodiment, the partburied in the gap part 31, of the light blocking layer 41, which isformed through burying of a light blocking material into the gap part 31between the lenses of the in-layer lenses 30 in the step of forming thelight blocking layer 41, is formed as the light blocker 40 provided onthe flat part 32. Therefore, the shape of the gap part 31 and the flatpart 32 formed together with the in-layer lens 30 in the step of formingthe in-layer lens 30 is utilized as the shape of the part where thelight blocker 40 is formed in the later step. Thus, the light blocker 40can be formed between the lenses of the in-layer lenses 30 withoutperforming positional alignment with the in-layer lens 30. As above,according to the method for manufacturing the solid-state imagingelement 1 in accordance with the present embodiment, the light blocker40 can be formed in a self-aligned manner.

If a light blocking film is deposited after the in-layer lenses 30 areformed and the light blocker is formed by patterning based on e.g.photolithography, pattern positional alignment with the in-layer lens 30is necessary and it is difficult to obtain high accuracy of patternalignment between the in-layer lens 30 and the light blocker. Thus, ifthe light blocker is formed by patterning, it is difficult to respond tomicrominiaturization and increase in the number of pixels in thesolid-state imaging element. In this regard, according to the method formanufacturing the solid-state imaging element 1 in accordance with thepresent embodiment, the light blocker 40 can be formed in a self-alignedmanner as described above. Thus, high accuracy of pattern alignmentbetween the in-layer lens 30 and the light blocker 40 can be obtainedand it is easy to respond to microminiaturization and increase in thenumber of pixels.

Furthermore, the method of forming the light blocker by patterning basedon e.g. photolithography needs a step of forming a mask and so forth andthus causes large increase in the number of steps. In this regard, inthe method for manufacturing the solid-state imaging element 1 accordingto the present embodiment, merely the following two steps are added tothe step of forming the in-layer lenses 30: the step of forming thelight blocking layer 41 and the step of etching to partially remove thelight blocking layer 41. Thus, the method does not cause large increasein the number of steps and is advantageous in terms of the cost.

Furthermore, in the method for manufacturing the solid-state imagingelement 1 according to the present embodiment, by using e.g. a metalsuch as tungsten as the material of the light blocker 40, high lightblocking capability can be achieved and color crosstalk can beeffectively reduced. In addition, using a metal as the material of thelight blocker 40 can achieve high heat resistance against a hightemperature process and widen the application range.

The light blocker 45 of the microlens 35 can also be formed by a methodsimilar to the above-described respective steps and the above-describedeffects can be achieved. Specifically, in the case of the light blocker45 of the microlens 35, according to the method for manufacturing thesolid-state imaging element 1 in accordance with the present embodiment,the light blocker 45 can be formed in a self-aligned manner in providingthe light blocker 45 at the boundary part between the lenses of themicrolenses 35 provided corresponding to the light receiving parts 3 ofthe respective pixels 7. Thus, the accuracy of pattern alignment betweenthe microlens 35 and the light blocker 45 can be enhanced and it ispossible to easily respond to microminiaturization and increase in thenumber of pixels.

However, the incident light corresponding to the gap part 31 of thein-layer lens 30 is nearly limited to a color crosstalk component.Therefore, in terms of prevention of sensitivity lowering due tovignetting of the incident light, providing the light blocker 40 for thein-layer lens 30 is more effective than providing the light blocker 45for the microlens 35.

Specifically, the light blocker 45 provided between the lenses of themicrolenses 35 often causes blocking of part of incident light, i.e.so-called vignetting of the incident light, and the vignetting of theincident light causes sensitivity lowering. In this regard, in the caseof the in-layer lens 30, the incident light on the gap part 31 is nearlylimited to a color crosstalk component as described above. Therefore, interms of keeping the sensitivity, the light blocker 40 of the in-layerlens 30 is preferentially employed compared with the light blocker 45 ofthe microlens 35.

Modification Example 1

A modification example of the method for manufacturing the solid-stateimaging element 1 according to the present embodiment will be describedwith use of FIGS. 7A to 7C. As shown in FIGS. 7A to 7C, in the presentmodification example, in-layer lenses 30A formed in the step of forminglenses are formed as digital lenses having a rectangular sectionalshape.

In the present modification example, a trench-like gap part 31A having arectangular shape in sectional view is formed as the concave part formedat the boundary part between the in-layer lenses 30A adjacent to eachother. Also when the in-layer lenses 30A are digital lenses in thismanner, a light blocker 40A can be formed on the flat part 32 as thebottom in the gap part 31A by a method similar to the above-describedrespective steps.

Specifically, as shown in FIG. 7A, the plural in-layer lenses 30Acorresponding to the light receiving parts 3 of the respective pixels 7are formed on the waveguide 21. Next, as shown in FIG. 7B, filmdeposition is performed on the in-layer lenses 30A formed on thewaveguide 21 by using a light blocking material and thereby a lightblocking layer 41A is formed. In the step of forming this light blockinglayer 41A, the light blocking material to form the light blocker 40A isso deposited as to fill the gap part 31A between the in-layer lenses 30Aadjacent to each other, so that the light blocking layer 41A is formed.Then, as shown in FIG. 7C, the light blocking layer 41A is so etchedthat the light blocking material is left at the boundary part betweenthe in-layer lenses 30A adjacent to each other. Thereby, the lightblocker 40A composed of the light blocking material is formed at theboundary part between the in-layer lenses 30A adjacent to each other.

In the above-described manner, also in the configuration including thein-layer lenses 30A formed as digital lenses, the light blocker 40A canbe formed between the lenses similarly to the case of the in-layer lens30 having a substantially elliptical shape or a substantially circularshape in sectional view as described above, and similar effects can beachieved.

Modification Example 2

Another modification example of the method for manufacturing thesolid-state imaging element 1 according to the present embodiment willbe described with use of FIGS. 8A to 8C. As shown in FIGS. 8A to 8C, inthe present modification example, in-layer lenses 30B formed in the stepof forming lenses are gapless lenses having no gap between the adjacentin-layer lenses 30B.

In the present modification example, as the concave part formed at theboundary part between the in-layer lenses 30B adjacent to each other, atrench part 33 having a substantially V-character shape in sectionalview is formed by end parts of curves having a substantially ellipticalshape or a substantially circular shape in sectional view. That is, inthe present modification example, the gap part 31 and the flat part 32shown in FIGS. 6A to 6C do not exist between the lenses adjacent to eachother and the in-layer lenses 30B adjacent to each other arecontinuously formed. Also when the in-layer lenses 30B are gaplesslenses in this manner, a light blocker 40B can be formed on the trenchpart 33 by a method similar to the above-described respective steps.

Specifically, as shown in FIG. 8A, the plural in-layer lenses 30Bcorresponding to the light receiving parts 3 of the respective pixels 7are formed on the waveguide 21. Next, as shown in FIG. 8B, filmdeposition is performed on the in-layer lenses 30B formed on thewaveguide 21 by using a light blocking material and thereby a lightblocking layer 41B is formed. In the step of forming this light blockinglayer 41B, the light blocking material to form the light blocker 40B isso deposited as to fill the trench part 33 between the in-layer lenses30B adjacent to each other, so that the light blocking layer 41B isformed. Then, as shown in FIG. 8C, the light blocking layer 41B is soetched that the light blocking material is left at the boundary partbetween the in-layer lenses 30B adjacent to each other. Thereby, thelight blocker 40B composed of the light blocking material is formed atthe boundary part between the in-layer lenses 30B adjacent to eachother.

In the above-described manner, also in the configuration including thein-layer lenses 30B formed as gapless lenses, the light blocker 40B canbe formed between the lenses similarly to the case of the in-layer lens30 having a substantially elliptical shape or a substantially circularshape in sectional view as described above, and similar effects can beachieved.

Furthermore, if the in-layer lenses 30B formed in the step of forminglenses are gapless lenses like in the present modification example, theconcave part between the lenses is shallower compared with the case inwhich a gap part (see the gap part 31 in FIG. 6A) exists between thelenses. Thus, e.g. in etching the light blocking layer 41B by dryetching, the etching gas sufficiently reaches even the light blockinglayer 41B existing at the concave part between the lenses and the lightblocking layer 41B at the concave part between the lenses can be surelyremoved.

Specifically, if the gap part 31 exists between the lenses of thein-layer lenses 30 as shown in FIG. 6A, the etching gas does notsufficiently go into the gap part 31 in the step of etching to removethe light blocking layer 41. As a result, for example as shown in FIG.9, sidewalls 41 s by the light blocking layer 41 that is not removed areformed around the in-layer lenses 30 over the light blocker 40. Thesidewalls 41 s by the light blocking material formed around the in-layerlenses 30 in this manner are not preferable in terms of ensuring thesensitivity. In this regard, in the case of the gapless in-layer lens30B like in the present modification example, the light blocking layer41B existing in the concave part between the lenses is also sufficientlyexposed to the etching gas. Thus, the sidewall 41 s is not formed andthe sensitivity can be ensured.

Modification Example 3

In the present modification example, in the step of forming the lightblocking layer 41, a step of forming an adhesion layer for allowingadhesion of the light blocking material to the material to form thein-layer lens 30 is carried out.

Specifically, as shown in FIG. 10A, an underlying film 42 as theadhesion layer is formed on the in-layer lenses 30 formed in the step offorming lenses before the light blocking layer 41 is formed. Theunderlying film 42 is conformally formed in such a manner as to totallycover the plural in-layer lenses 30 and the flat parts 32 existing atthe boundary part between them. The underlying film 42 is formed by e.g.a sputtering method.

After the underlying film 42 is formed, as shown in FIG. 10B, the lightblocking material to form the light blocker 40 (see FIG. 6C) isdeposited on the underlying film 42 in such a manner as to fill the gappart 31 between the in-layer lenses 30 adjacent to each other. Thereby,the light blocking layer 41 is formed.

As described above, the adhesion of the material of the light blockinglayer 41 to the material of the in-layer lens 30 is affected by thecombination of the materials of the in-layer lens 30 and the lightblocking layer 41. So, like in the present modification example, theunderlying film 42 may be formed by using a material having favorableadhesion to both the material of the in-layer lens 30 and the materialof the light blocking layer 41 depending on the combination of thematerials of the in-layer lens 30 and the light blocking layer 41.

For example, if the material of the in-layer lens 30 is SiN (siliconnitride) and the material of the light blocking layer 41 is tungsten,the underlying film 42 is deposited by using SiO₂ as its material. Thatis, in this case, one layer of the underlying film 42 composed of SiO₂is formed on a SiN film including the in-layer lenses 30 and the flatparts 32 and the light blocking layer 41 is formed on this underlyingfilm 42. Examples of the material of the light blocking layer 41 includeAl (aluminum) besides W (tungsten), and examples of the material of theunderlying film 42 include Ti (titanium), Al₂O₃ (aluminum oxide), HfO₂(hafnium oxide), and TiO₂ (titanium dioxide) besides SiO₂. Thesematerials are used as the materials of the light blocking layer 41 andthe underlying film 42 in an appropriate combination.

As above, in the present modification example, the step of forming thelight blocking layer 41 has the step of forming the underlying film 42for allowing adhesion of the light blocking material to the material toform the in-layer lens 30, and the light blocking layer 41 formed overthe in-layer lenses 30 has a multilayer structure including theunderlying film 42 interposed between the light blocking layer 41 andthe in-layer lenses 30. This can enhance the adhesion of the lightblocker 40 formed between the lenses of the in-layer lenses 30 to thematerial of the in-layer lens 30. In the present embodiment, regardingthe light blocker 40 finally formed on the bottom of the gap part 31,mainly adhesion to the flat part 32 can be enhanced through forming ofthe light blocker 40 on the underlying film 42.

[Second Embodiment]

A second embodiment of the present technique will be described. In therespective embodiments to be described below, description of the partcommon to the first embodiment is accordingly omitted through use of thesame numeral and so forth, and different part will be intensivelydescribed. A method for manufacturing the solid-state imaging element 1according to the present embodiment is different from the firstembodiment in that it includes a step of forming an etching stopper film51 on the in-layer lenses 30 between the step of forming the in-layerlenses 30 and the step of forming the light blocking layer 41.

In the method for manufacturing the solid-state imaging element 1 of thepresent embodiment, as shown in FIG. 11A, first the in-layer lenses 30are formed on the waveguide 21 by using e.g. SiN. Thereafter, as shownin FIG. 11B, the etching stopper film 51 is formed on the in-layerlenses 30.

The etching stopper film 51 is a film for preventing etching of thein-layer lens 30 in etching for the light blocking layer 41 in the stepof forming the light blocker 40. Therefore, the etching stopper film 51is formed as a film having different etching characteristics from thelight blocking layer 41. That is, the etching stopper film 51 is formedby a material having high etching selectivity with respect to the lightblocking material to form the light blocking layer 41.

The etching stopper film 51 is conformally formed in such a manner as tototally cover the plural in-layer lenses 30 and the flat parts 32existing at the boundary part between them. The etching stopper film 51is formed by e.g. a sputtering method. The etching stopper film 51 isformed with a film thickness of e.g. several tens to hundreds ofnanometers. As the material to form the etching stopper film 51, e.g.SiO₂ (silicon oxide film) is used.

In the method for manufacturing the solid-state imaging element 1according to the present embodiment, it is preferable to use a materialhaving a refractive index that is lower than that of the material toform the in-layer lens 30 and higher than that of the material of thelayer formed over the in-layer lenses 30 with the intermediary of theetching stopper film 51 as the material to form the etching stopper film51. The layer formed over the in-layer lenses 30 with the intermediaryof the etching stopper film 51 is the layer formed on the etchingstopper film 51 formed on the in-layer lenses 30 in the solid-stateimaging element 1. In the solid-state imaging element 1 of the presentembodiment, this layer is the passivation film 24 (see FIG. 2).

As described above, the in-layer lenses 30 are formed by using amaterial having a refractive index higher than that of the material toconfigure the layer or film formed on the in-layer lenses 30, i.e. thematerial to form the passivation film 24. So, in the configuration inwhich the etching stopper film 51 is formed on the in-layer lenses 30like in the present embodiment, it is preferable to select materialssatisfying such a relationship that the in-layer lens 30, the etchingstopper film 51, and the passivation film 24 are in decreasing order ofthe refractive index of the material.

That is, when the refractive indexes of the material to form thein-layer lens 30, the material to form the etching stopper film 51, andthe material to configure the passivation film 24 formed on the in-layerlenses 30 are defined as n1, n2, and n3, respectively, preferably amaterial satisfying a relationship of n1>n2>n3 is used as the materialto form the etching stopper film 51.

Specifically, for example when the material to form the in-layer lens 30is SiN (silicon nitride) and the material to form the passivation film24 is a SiO₂ film (silicon oxide film), SiON (silicon oxynitride film),which is a material having an intermediate refractive index with respectto SiN and SiO₂, is used as the material of the etching stopper film 51.When the wavelength of light is 550 nm, the refractive index of SiN (n1)can be adjusted in a range of about 1.8 to 2.1 depending on thefabrication method and so forth. In addition, the refractive index ofSiON (n2) is about 1.5 to 1.8 and the refractive index of SiO₂ (n3) is1.4 to 1.5.

Furthermore, for example when the material to form the in-layer lens 30is SiN (silicon nitride) and a SiO₂ film (silicon oxide film) is used asthe material to form the etching stopper film 51, a material having arefractive index lower than that of SiO₂ is used as the material to formthe passivation film 24.

By using a material having a refractive index that is lower than that ofthe material of the in-layer lens 30 and higher than that of thematerial of the layer formed over the in-layer lenses 30 with theintermediary of the etching stopper film 51 as the material to form theetching stopper film 51 in this manner, the etching stopper film 51 canbe made to function as an antireflection film against light incident onthe in-layer lens 30. That is, the etching stopper film 51 can be madeto serve also as the antireflection film by making the material to formthe etching stopper film 51 satisfy the above-described refractive indexcondition with respect to the materials of the layer structures existingon and under the etching stopper film 51.

After the etching stopper film 51 is formed on the in-layer lenses 30 asshown in FIG. 11B, film deposition is performed on the etching stopperfilm 51 covering the in-layer lenses 30 by using a light blockingmaterial and thereby the light blocking layer 41 is formed as shown inFIG. 11C. In the step of forming this light blocking layer 41, the lightblocking material to form the light blocker 40 is deposited on theetching stopper film 51 by e.g. sputtering or CVD in such a manner as tofill the gap part 31 between the in-layer lenses 30 adjacent to eachother, so that the light blocking layer 41 is formed.

Then, as shown in FIG. 11D, the light blocking layer 41 is so etchedthat the light blocking material is left at the boundary part betweenthe in-layer lenses 30 adjacent to each other. Thereby, the lightblockers 40 composed of the light blocking material are formed at theboundary parts between the in-layer lenses 30 adjacent to each other. Inthe present embodiment, the light blockers 40 are formed on the etchingstopper film 51 deposited on the in-layer lenses 30 and the flat parts32.

In this etching step, the light blocking layer 41 is partially removedin such a manner that the light blocking layer 41 with a predeterminedfilm thickness is left over the flat parts 32 between the lenses of thein-layer lenses 30 with the intermediary of the etching stopper film 51and the light blockers 40 are formed by the material of the lightblocking layer 41. At this time, the etching is so performed that thelight blocking layer 41 is not left on the in-layer lenses 30 and theetching stopper film 51 is not removed.

To perform such selective etching, an etching condition that provideshigh etching selectivity between the material of the etching stopperfilm 51 and the material of the light blocking layer 41 is employed.That is, because the etching stopper film 51 is formed by using amaterial having high etching selectivity with respect to the lightblocking material to form the light blocking layer 41 as describedabove, selective etching of the light blocking layer 41 can beperformed. For example, if the material of the light blocking layer 41is tungsten and the material of the etching stopper film 51 is SiON, anetching condition that provides high etching selectivity betweentungsten and SiON is employed.

In the present embodiment, dry etching is performed as the etching ande.g. the following condition is used as its etching condition. As theetching gas, a mixed gas of SF₆ (sulfur hexafluoride), Cl₂ (chlorine),O₂ (oxygen), and N₂ (nitrogen) is used. The respective gases are used atthe following flow rates: 100 [ml/min] for SF₆; 50 [ml/min] for Cl₂; 10[ml/min] for O₂; and 50 [ml/min] for N₂. The pressure of the treatmentatmosphere is set to 0.5 [Pa]. The source power is set to about 500 [W]and the bias power applied to the wafer side (side of the semiconductorsubstrate 11) is set to about 50 [W]. The temperature of the stage onwhich the etching treatment target is placed is set to about 25 [° C.].The final film thickness of the light blocker 40 is adjusted by timecontrol in the etching or end point detection.

In the above-described manner, the light blocker 40 of the in-layer lens30 included in the solid-state imaging element 1 of the presentembodiment is formed. According to the method in which the step offorming the etching stopper film 51 is carried out between the step offorming the in-layer lenses 30 and the step of forming the lightblocking layer 41 like the manufacturing method of the presentembodiment, etching of the in-layer lens 30 in the etching step can beavoided irrespective of the etching selectivity between the material ofthe in-layer lens 30 and the light blocking material of the lightblocking layer 41. That is, the manufacturing method of the presentembodiment is preferably used when it is difficult to ensure highetching selectivity between the material of the in-layer lens 30 and thelight blocking material of the light blocking layer 41.

[Third Embodiment]

A third embodiment of the present technique will be described. A methodfor manufacturing the solid-state imaging element 1 according to thepresent embodiment is different from the above-described respectiveembodiments in that a light blocking layer formed on the in-layer lenses30 is conformally deposited and then a planarization resist film isapplied on the light blocking layer.

In the method for manufacturing the solid-state imaging element 1according to the present embodiment, as shown in FIG. 12A, first thein-layer lenses 30 are formed on the waveguide 21 by using e.g. SiN.Thereafter, as shown in FIG. 12B, the etching stopper film 51 is formedon the in-layer lenses 30.

Next, as shown in FIG. 12C, film deposition is performed on the etchingstopper film 51 covering the in-layer lenses 30 by using a lightblocking material and thereby a light blocking layer 41C is formed. Inthe present embodiment, the light blocking layer 41C is conformallydeposited. That is, from the state in which the etching stopper film 51is conformally formed in such a manner as to totally cover the pluralin-layer lenses 30 and the flat parts 32 existing at the boundary partbetween them, the light blocking layer 41C is so deposited as to bestacked on the etching stopper film 51 and follow the shape of thein-layer lenses 30 and the flat parts 32.

As the method for conformally depositing the light blocking layer 41C,sputtering is preferably used. However, the method for depositing thelight blocking layer 41C is not limited and another film depositionmethod such as CVD can be accordingly used.

Subsequently, as shown in FIG. 12D, a planarization resist film 61 isapplied on the light blocking layer 41C conformally deposited. Apublicly-known resist material can be used as the material of theplanarization resist film 61. The planarization resist film 61 is formedto such a thickness that at least a flat surface 61 a is formed.Therefore, the planarization resist film 61 is formed to a thicknesslarger than the height along the shape of the in-layer lens 30 regardingthe light blocking layer 41C conformally deposited on the in-layerlenses 30 (see symbol D1).

Then, as shown in FIG. 12E, the light blocking layer 41C and theplanarization resist film 61 are so etched that the light blockingmaterial is left at the boundary part between the in-layer lenses 30adjacent to each other. Thereby, the light blockers 40 composed of thelight blocking material are formed at the boundary parts between thein-layer lenses 30 adjacent to each other.

In this etching step, the light blocking layer 41C is partially removedin such a manner that the light blocking layer 41C with a predeterminedfilm thickness is left over the flat parts 32 between the lenses of thein-layer lenses 30 with the intermediary of the etching stopper film 51and the light blockers 40 are formed by the material of the lightblocking layer 41C. In addition, the planarization resist film 61 istotally removed. At this time, the etching is so performed that theplanarization resist film 61 and the light blocking layer 41C are notleft on the in-layer lenses 30 and the etching stopper film 51 is notremoved.

To perform such selective etching, etch-back of the whole surface fromthe side of the flat surface 61 a of the planarization resist film 61 isperformed by dry etching in the present embodiment. Furthermore, anetching condition is employed that provides a ratio of 1 to 1 as theetching selectivity of the material of the planarization resist film 61to the material of the light blocking layer 41C and provides highetching selectivity between the material of the etching stopper film 51and the material of the light blocking layer 41C.

Specifically, the light blockers 40 with a predetermined film thicknessare obtained between the lenses of the in-layer lenses 30 throughuniform etching of the planarization resist film 61 and the lightblocking layer 41C along the flat surface 61 a. Therefore, theplanarization resist film 61 and the light blocking layer 41C are etchedwith selectivity of 1 to 1. Furthermore, because the etching stopperfilm 51 should be left on the in-layer lenses 30, the light blockinglayer 41C is selectively etched with the etching stopper film 51 left.

In the present embodiment, in order to perform etching of theplanarization resist film 61 and the light blocking layer 41C withselectivity of 1 to 1, e.g. the following condition is used as theetching condition, differently from the etching condition shown as anexample for the second embodiment. If the material of the light blockinglayer 41C is W (tungsten) and the material of the etching stopper film51 is SiO₂, a mixed gas of SF₆ (sulfur hexafluoride), Cl₂ (chlorine),and O₂ (oxygen) is used as the etching gas. The respective gases areused at the following flow rates: 30 [ml/min] for SF₆; 100 [ml/min] forCl₂; and 50 [ml/min] for O₂. The source power is set to about 1000 [W]and the bias power is set to about 50 [W].

As described above, in the present embodiment, the light blockingmaterial is conformally deposited in the step of forming the lightblocking layer 41C, and the step of applying the planarization resistfilm 61 on the light blocking layer 41C is further carried out betweenthe step of forming the light blocking layer 41C and the step of formingthe light blockers 40. In the step of forming the light blockers 40, theplanarization resist film 61 is etched together with the light blockinglayer 41C.

According to the method for manufacturing the solid-state imagingelement 1 in accordance with the present embodiment, even if sufficientfilling capability of the light blocking material for the gap part 31between the lenses of the in-layer lenses 30 is not obtained in the stepof forming the light blocking layer 41C, it is possible to easilyrespond to this situation. That is, the method for manufacturing thepresent embodiment is preferably used if it is difficult to perform suchfilm deposition as to fill the gap part 31 between the lenses of thein-layer lenses 30 in the step of forming the light blocking layer 41C.Examples of the case in which it is difficult to perform such filmdeposition as to fill the gap part 31 between the lenses of the in-layerlenses 30 includes the case in which the CVD method, by which highfilling capability is obtained as described above, cannot be usedbecause of instability in terms of the process.

Furthermore, the following collateral effect is also obtained accordingto the method for manufacturing the solid-state imaging element 1 inaccordance with the present embodiment. In the solid-state imagingelement 1, a wiring area exists around the imaging area 2, in which thepixels 7 are arranged. Thus, after forming of the light blocking layer41C, the light blocking material to form the light blocking layer 41C isoften left also in this peripheral wiring area of the imaging area 2. Insuch a case, the light blocking material in the peripheral wiring areaneeds to be removed by e.g. etching, with the imaging area 2 masked byresist.

In this regard, by employing the method for manufacturing thesolid-state imaging element 1 according to the present embodiment, afterthe planarization resist film 61 is applied on the light blocking layer41C, the etching for forming the light blockers 40 can be performedafter the part of the planarization resist film 61 in the peripheralwiring area is removed by exposure in advance. This can eliminate theabove-described step of removing the light blocking material in theperipheral wiring area.

[Fourth Embodiment]

A fourth embodiment of the present technique will be described. A methodfor manufacturing the solid-state imaging element 1 according to thepresent embodiment is different from the above-described thirdembodiment mainly in that it includes a step of forming a hard mask inthe gap between the lenses of the in-layer lenses 30 on a conformallight blocking layer after conformally depositing the light blockinglayer formed on the in-layer lenses 30.

In the method for manufacturing the solid-state imaging element 1according to the present embodiment, as shown in FIG. 13A, first thein-layer lenses 30 are formed on the waveguide 21 by using e.g. SiN.Thereafter, as shown in FIG. 13B, the etching stopper film 51 is formedon the in-layer lenses 30. Next, as shown in FIG. 13C, film depositionis conformally performed on the etching stopper film 51 covering thein-layer lenses 30 by using a light blocking material and thereby thelight blocking layer 41C is formed.

Subsequently, as shown in FIG. 13D, a hard mask 71 is formed on thelight blocking layer 41C conformally deposited. The hard mask 71functions as a hard mask in etching in the step of forming the lightblockers 40 and is e.g. an oxide film.

The hard mask 71 is selectively formed in such a manner as to fill thegap part 31 at the boundary part between the in-layer lenses 30 adjacentto each other. Specifically, as shown in FIG. 13D, on the light blockinglayer 41C in the gap part 31 between the lenses of the in-layer lenses30, the hard mask 71 is formed to a position lower than the peak part ofthe light blocking layer 41C on the in-layer lens 30. At the part otherthan the gap part 31 on the light blocking layer 41C, the hard mask 71is formed with a comparatively small thickness.

The hard mask 71 is formed through coating of a resin film as aspin-on-glass (SOG) film for example. Alternatively, the hard mask 71 isformed as borophosphosilicate glass (BPSG) or a silicon oxide film(SiO₂) by a CVD method with use of a tetraethoxysilane (TEOS) gas forexample. More alternatively, the hard mask 71 is formed as a SiO₂-basedCVD film by a bias high density plasma CVD method for example.

After the hard mask 71 is formed, as shown in FIG. 13E, the lightblocking layer 41C and the hard mask 71 are so etched that the lightblocking material is left at the boundary part between the in-layerlenses 30 adjacent to each other and thereby the light blockers 40composed of the light blocking material are formed at the boundary partsbetween the in-layer lenses 30 adjacent to each other.

In this etching step, the light blocking layer 41C and the hard mask 71are partially removed in such a manner that the light blocking layer 41Cwith a predetermined film thickness is left over the flat parts 32between the lenses of the in-layer lenses 30 with the intermediary ofthe etching stopper film 51 and the light blockers 40 are formed by thematerial of the light blocking layer 41C. At this time, the lightblocking layer 41C is etched after the comparatively-thin hard mask 71formed on the light blocking layer 41C at the peak part of the in-layerlens 30 is removed ahead. Furthermore, the etching is so performed thatthe light blocking layer 41C is not left on the in-layer lenses 30 andthe etching stopper film 51 is not removed.

To perform such selective etching, in the present embodiment, an etchingcondition that provides high etching selectivity between the material ofthe above-described etching stopper film 51 and the material of thelight blocking layer 41C is employed. As shown in FIG. 13E, in thepresent embodiment, remaining films 71 a of the hard mask 71 exist onthe light blockers 40 after the etching step depending on the case.

As described above, in the present embodiment, the light blockingmaterial is conformally deposited in the step of forming the lightblocking layer 41C, and the step of forming the hard mask 71 at theboundary part between the in-layer lenses 30 on the light blocking layer41C is further carried out between the step of forming the lightblocking layer 41C and the step of forming the light blockers 40.

According to the method for manufacturing the solid-state imagingelement 1 in accordance with the present embodiment, even if sufficientfilling capability of the light blocking material for the gap part 31between the lenses of the in-layer lenses 30 is not obtained in the stepof forming the light blocking layer 41C and it is difficult to provide aratio of 1 to 1 as the etching selectivity between the planarizationresist film 61 and the light blocking layer 41C in the etching (see thethird embodiment), it is possible to easily respond to this situation.That is, the manufacturing method of the present embodiment ispreferably used if it is difficult to perform such film deposition as tofill the gap part 31 between the lenses of the in-layer lenses 30 in thestep of forming the light blocking layer 41C and it is difficult toprovide a ratio of 1 to 1 as the etching selectivity between theplanarization resist film 61 and the light blocking layer 41C. Examplesof the cause of the difficulty in providing a ratio of 1 to 1 as theetching selectivity between the planarization resist film 61 and thelight blocking layer 41C include instability of the flow rate of theetching gas and the etching characteristics of the metal material toform the light blocking layer 41C.

Modification Example

A modification example of the method for manufacturing the solid-stateimaging element 1 according to the present embodiment will be described.In the present modification example, a non-doped silicate glass (NSG)film is formed as the hard mask formed on the light blocking layer 41Cconformally deposited.

In the case of employing the NSG film as the hard mask in this manner,dry etching is performed as the etching in the step of forming the lightblockers 40 and e.g. the following condition is used as the etchingcondition. As the etching gas, a mixed gas of Ar (argon), CF₄ (carbontetrafluoride), and CHF₃ (trifluoromethane) is used. The respectivegases are used at the following flow rates: 200 [ml/min] for Ar; 20[ml/min] for CF₄; and 15 [ml/min] for CHF₃. The pressure of thetreatment atmosphere is set to 1.5 [Pa]. The source power is set toabout 700 [W] and the bias power applied to the wafer side (side of thesemiconductor substrate 11) is set to about 70 [W]. The temperature ofthe stage on which the etching treatment target is placed is set toabout 25 [° C.]. The final film thickness of the light blocker 40 isadjusted by time control in the etching.

The same effects can be achieved also by forming the NSG film instead ofan oxide film or the like as the hard mask formed on the light blockinglayer 41C conformally deposited in this manner.

[Fifth Embodiment]

A fifth embodiment of the present technique will be described. A methodfor manufacturing the solid-state imaging element 1 according to thepresent embodiment is different from the above-described fourthembodiment in that the light blocking layer 41 is so formed as to fillthe gap part 31 between the in-layer lenses 30 adjacent to each other inthe step of forming the light blocking layer 41.

In the method for manufacturing the solid-state imaging element 1according to the present embodiment, as shown in FIG. 14A, first thein-layer lenses 30 are formed on the waveguide 21 by using e.g. SiN.Thereafter, as shown in FIG. 14B, the etching stopper film 51 is formedon the in-layer lenses 30. Next, as shown in FIG. 14C, film depositionis performed on the etching stopper film 51 covering the in-layer lenses30 by using a light blocking material in such a manner as to fill thegap part 31 between the lenses of the in-layer lenses 30 and thereby thelight blocking layer 41 is formed.

Subsequently, as shown in FIG. 14D, a hard mask 71A is formed on thelight blocking layer 41 deposited to fill the gap part 31. The hard mask71A is selectively formed in such a manner as to fill the gap part 31 atthe boundary part between the in-layer lenses 30 adjacent to each other.Specifically, as shown in FIG. 14D, on the light blocking layer 41 inthe gap part 31 between the lenses of the in-layer lenses 30, the hardmask 71A is formed to a position lower than the peak of the lightblocking layer 41 on the in-layer lens 30. At the part other than thegap part 31, including the peak, on the light blocking layer 41, thehard mask 71A is formed with a comparatively small thickness.

After the hard mask 71A is formed, as shown in FIG. 14E, the lightblocking layer 41 and the hard mask 71A are so etched that the lightblocking material is left at the boundary part between the in-layerlenses 30 adjacent to each other and thereby light blockers 80 composedof the light blocking material are formed at the boundary parts betweenthe in-layer lenses 30 adjacent to each other.

In this etching step, the light blocking layer 41 and the hard mask 71Aare partially removed in such a manner that the light blocking layer 41with a predetermined film thickness is left over the flat parts 32between the lenses of the in-layer lenses 30 with the intermediary ofthe etching stopper film 51 and the light blockers 80 are formed by thematerial of the light blocking layer 41. At this time, the lightblocking layer 41 is etched after the comparatively-thin hard mask 71Aformed on the light blocking layer 41 at the peak part of the in-layerlens 30 is removed ahead. Furthermore, the etching is so performed thatthe light blocking layer 41 is not left on the in-layer lenses 30 andthe etching stopper film 51 is not removed.

To perform such selective etching, in the present embodiment, an etchingcondition that provides high etching selectivity between the material ofthe above-described etching stopper film 51 and the material of thelight blocking layer 41 is employed.

Furthermore, isotropic etching is performed in the etching step so thatthe light blockers 80 may be formed through processing of the lightblocking layer 41 into pillar shapes as shown in FIG. 14E. Specifically,according to the manufacturing method of the present embodiment, thelight blocker 80 formed at the boundary part between the in-layer lenses30 adjacent to each other is formed not only on the bottom of the gappart 31 but also to the upper area of the gap part 31 as a pillarportion. Remaining films 71Aa of the hard mask 71A exist on the lightblockers 80. Therefore, the height (film thickness) of the light blocker80 is equal to the film thickness of the part of the light blockinglayer 41 deposited to fill the gap part 31.

As described above, in the present embodiment, the light blockingmaterial is so deposited as to fill the gap part 31 in the step offorming the light blocking layer 41, and the step of forming the hardmask 71A at the boundary part between the in-layer lenses 30 on thelight blocking layer 41 is further carried out between the step offorming the light blocking layer 41 and the step of forming the lightblockers 80.

According to the method for manufacturing the solid-state imagingelement 1 in accordance with the present embodiment, the light blocker80 can be formed not only on the bottom of the gap part 31 between thelenses but also to the upper area of the gap part 31 without spoilingthe lens function of the in-layer lenses 30. Thus, the light blockingfunction by the light blocker 80 can be enhanced. In particular, highlight blocking capability against oblique light whose incident angle islarge is obtained. Due to this feature, a structure having a high colorcrosstalk prevention effect can be achieved in the solid-state imagingelement 1. Also in the present embodiment, an NSG film can be employedas the hard mask similarly to the modification example of the fourthembodiment.

[Film Deposition Condition]

The manufacturing methods of the above-described respective embodimentsare manufacturing methods based on the assumption that the material ofthe in-layer lens 30 is an inorganic material, such as SiN (siliconnitride), permitting a high temperature process. Therefore, for exampleif the material of the in-layer lens 30 is e.g. a resin, the in-layerlens 30 cannot withstand the high temperature process in some cases.

So, in the step of forming the light blocking layer 41 and the step offorming the etching stopper film 51, a temperature condition under whichthe temperature of the in-layer lens 30 is at most 200° C. can be usedas the film deposition condition of the light blocking layer 41 or theetching stopper film 51. That is, a low temperature process at atemperature of at most 200° C. is desirable if a lens incapable ofwithstanding a high temperature process, such as a resin lens, is usedas the in-layer lens 30. Specifically, the process is as follows.

For example, as shown in FIG. 14A, the in-layer lenses 30 are formed onthe waveguide 21 by using e.g. SiN. Thereafter, as shown in FIG. 14B,the etching stopper film 51 is formed on the in-layer lenses 30. As theetching stopper film 51, a SiO₂ (silicon oxide film) is conformallydeposited with a film thickness of several tens to hundreds ofnanometers under a temperature condition of at most 200° C. for example.

Next, as shown in FIG. 14C for example, film deposition is performed onthe etching stopper film 51 covering the in-layer lenses 30 by using alight blocking material in such a manner as to fill the gap part 31between the lenses of the in-layer lenses 30 and thereby the lightblocking layer 41 is formed. In this step, the light blocking layer 41is formed under a film deposition condition at a temperature of at most200° C. As the method for forming the light blocking layer 41 under afilm deposition condition at a temperature of at most 200° C., e.g. asputtering method, evaporation, or physical vapor deposition (PVD) ispreferably used. Thereafter, the step of forming the light blockers 40between the lenses by etching is carried out through e.g. the step offorming the hard mask 71 similarly to the above-described respectiveembodiments.

As described above, if a lens incapable of withstanding a hightemperature process, such as a resin lens, is used as the in-layer lens30, it is preferable to perform film deposition of the light blockinglayer 41 and the etching stopper film 51 under a temperature conditionin which the temperature of the in-layer lens 30 is at most 200° C. inthe step of forming the light blocking layer 41 and the step of formingthe etching stopper film 51. This makes it possible to form the lightblockers 40 between the lenses of the in-layer lenses 30 even if thein-layer lens 30 is a lens incapable of withstanding a comparativelyhigh temperature process, such as a resin lens. If the step of formingthe etching stopper film 51 is not carried out, a temperature conditionof at most 200° C. is used as the film deposition condition of the lightblocking layer 41 in the step of forming the light blocking layer 41.

In the second to fifth embodiments explained above, the in-layer lens 30may be a digital lens (see FIGS. 7A to 7C) or a gapless lens (see FIGS.8A to 8C) and the light blocking layer 41 may have a multilayerstructure including the underlying film 42 as an adhesion layer (seeFIGS. 10A and 10B) similarly to the first embodiment, and the sameeffects can be achieved.

[Configuration Example of Electronic Apparatus]

The solid-state imaging elements according to the above-describedembodiments are applied to various kinds of electronic apparatus such asdigital still camera referred to as the so-called digital camera,digital video camcorder, cellular phone having an imaging function, andother pieces of apparatus. In the following, a video camcorder 100 asone example of electronic apparatus including the solid-state imagingelement according to the above-described embodiment will be describedwith use of FIG. 15.

The video camcorder 100 performs photographing of still images or movingimages. The video camcorder 100 has a solid-state imaging element 101according to the above-described embodiment, an optical system 102, ashutter device 103, a drive circuit 104, and a signal processing circuit105.

The optical system 102 is configured as e.g. an optical lens systemhaving one or plural optical lenses and guides incident light to lightreceiving parts (light receiving parts 3) of the solid-state imagingelement 101. The optical system 102 forms an image on the imaging planeof the solid-state imaging element 101 based on image light (incidentlight) from a subject. Thereby, a signal charge is accumulated in thesolid-state imaging element 101 for a certain period. The shutter device103 is a configuration for controlling the period of light irradiationto the solid-state imaging element 101 and the light blocking period.

The drive circuit 104 drives the solid-state imaging element 101. Thedrive circuit 104 generates a drive signal (timing signal) for drivingthe solid-state imaging element 101 at a predetermined timing andsupplies it to the solid-state imaging element 101. By the drive signalsupplied from the drive circuit 104 to the solid-state imaging element101, transfer operation of the signal electrode of the solid-stateimaging element 101 and so forth are controlled. That is, thesolid-state imaging element 101 carries out the transfer operation ofthe signal charge and so forth based on the drive signal supplied fromthe drive circuit 104.

The drive circuit 104 has a function to generate various kinds of pulsesignals as drive signals for driving the solid-state imaging element 101and a function as a driver that converts the generated pulse signals todrive pulses for driving the solid-state imaging element 101. The drivecircuit 104 also generates and supplies a drive signal for controllingthe operation of the shutter device 103.

The signal processing circuit 105 has a function to execute variouskinds of signal processing and processes an output signal of thesolid-state imaging element 101. The signal processing circuit 105processes the input signal to thereby output a video signal. The videosignal output from the signal processing circuit 105 is stored in astorage medium such as a memory and output to a monitor. The videocamcorder 100 has a power supply section such as a battery that suppliespower to the drive circuit 104 and so forth, a storage section thatstores the video signal generated by imaging and so forth, a controlsection that controls the whole device, etc.

The video camcorder 100 of the present embodiment encompasses also aform of a camera module or an imaging function module obtained byintegrating the solid-state imaging element 101, the optical system 102,the shutter device 103, the drive circuit 104, and the signal processingcircuit 105 into a module.

According to the video camcorder 100 that has the above-describedconfiguration and includes the solid-state imaging element 101 of thepresent embodiment, color crosstalk at the boundary part between theadjacent pixels 7 of colors different from each other can be reduced dueto provision of the light blockers 40 at the boundary parts between thein-layer lenses 30 adjacent to each other. Furthermore, because thelight blockers 40 are composed of a metal, high light blockingcapability can be achieved. In addition, high heat resistance thatallows withstanding even against a high temperature process can beachieved, so that the application range can be widened.

Furthermore, by employing the method for manufacturing the solid-stateimaging element according to any of the above-described respectiveembodiments as the step of manufacturing the solid-state imaging element101 included in the video camcorder 100, the light blockers 40 can beformed in a self-aligned manner in providing the light blockers 40 atthe boundary parts between the lenses of the in-layer lenses 30 providedcorresponding to the light receiving parts 3 of the respective pixels 7.Thus, the accuracy of pattern alignment between the in-layer lens 30 andthe light blocker 40 can be enhanced and it is possible to easilyrespond to microminiaturization and increase in the number of pixels.

The present technique can have the following configurations.

(1) A method for manufacturing a solid-state imaging element, the methodincluding forming lenses that are each provided corresponding to a lightreceiving part of a respective one of a plurality of pixels arranged inan imaging area over a semiconductor substrate and collect light ontothe light receiving parts, forming a light blocking layer by performingfilm deposition on the lenses by using a material having light blockingcapability, and forming a light blocker composed of the material havinglight blocking capability at a boundary part between the lenses adjacentto each other by etching the light blocking layer in such a manner thatthe material having light blocking capability is left at the boundarypart between the lenses.

(2) The method for manufacturing a solid-state imaging element accordingto (1), wherein the material having light blocking capability is ametal.

(3) The method for manufacturing a solid-state imaging element accordingto (1) or (2), wherein the forming the light blocking layer includesforming an adhesion layer for allowing adhesion of the material havinglight blocking capability to a material to form the lenses.

(4) The method for manufacturing a solid-state imaging element accordingto one of (1) to (3), further including forming an etching stopper filmon the lenses by using a material having etching selectivity withrespect to the material having light blocking capability, between theforming the lenses and the forming the light blocking layer.

(5) The method for manufacturing a solid-state imaging element accordingto (4), wherein a material having a refractive index that is lower thana refractive index of a material to form the lenses and is higher than arefractive index of a material of a layer formed over the lenses withintermediary of the etching stopper film is used as the material havingetching selectivity.

(6) The method for manufacturing a solid-state imaging element accordingto (4) or (5), wherein film deposition of the light blocking layer andthe etching stopper film is performed under a temperature condition inwhich temperature of the lenses is at most 200° C., in the forming thelight blocking layer and the forming the etching stopper film.

(7) The method for manufacturing a solid-state imaging element accordingto one of (1) to (6), further including applying a planarization resistfilm over the light blocking layer, between the forming the lightblocking layer and the forming the light blocker, wherein the materialhaving light blocking capability is conformally deposited in the formingthe light blocking layer, and the planarization resist film is etchedtogether with the light blocking layer in the forming the light blocker.

(8) The method for manufacturing a solid-state imaging element accordingto one of (1) to (6), further including forming a hard mask at theboundary part between the lenses on the light blocking layer, betweenthe forming the light blocking layer and the forming the light blocker.

(9) The method for manufacturing a solid-state imaging element accordingto (8), wherein the material having light blocking capability isconformally deposited in the forming the light blocking layer.

(10) The method for manufacturing a solid-state imaging elementaccording to one of (1) to (9), wherein the lenses are gapless lenseshaving no gap between the lenses adjacent to each other.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-142428 filed in theJapan Patent Office on Jun. 28, 2011, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors in so far as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A solid-state imaging element comprising: aplurality of pixels arranged in an imaging area over a semiconductorsubstrate, each of the plurality of pixels including a light receivingpart configured to accumulate a signal charge through photoelectricconversion of incident light; color filters, each provided for arespective one of the plurality of pixels; a first set of roundedlenses, each provided over a light receiving part of the respective oneof the plurality of pixels and each being configured to collect lightonto the light receiving part; a second set of rounded lenses, eachprovided over one of the first set of rounded lenses, and each beingconfigured to collect light onto the one of the first set of roundedlenses; and a light blocker provided at a boundary between adjacentlenses of the first set of rounded lenses and a light blocker providedat a boundary between adjacent lenses of the second set of roundedlenses, wherein the light blocker provided at the boundary betweenadjacent lenses of the first set of rounded lenses is larger than thelight blocker provided at the boundary between adjacent lenses of thesecond set of rounded lenses.
 2. The solid-state imaging elementaccording to claim 1, wherein the second set of rounded lenses areon-chip lenses provided on the color filters.
 3. The solid-state imagingelement according to claim 2, wherein the first set of rounded lensesare in-layer lenses provided inside a layer-laminated structureconfiguring the pixels.
 4. The solid-state imaging element according toclaim 1, wherein the first set of rounded lenses are linked atboundaries thereof by a film formed therewith and the second set ofrounded lenses are linked at boundaries thereof by a film formedtherewith.
 5. The solid-state imaging element according to claim 1,wherein the light blocker is metal.
 6. An electronic apparatus,comprising: a solid-state imaging element, an optical system that guidesincident light to light receiving parts of the solid-state imagingelement, a drive circuit that generates a drive signal for driving thesolid-state imaging element, and a signal processing circuit thatprocesses an output signal of the solid-state imaging element, thesolid-state imaging element comprising: a plurality of pixels arrangedin an imaging area over a semiconductor substrate, each of the pluralityof pixels including one of the light receiving parts that accumulatesignal charge through photoelectric conversion of incident light; colorfilters, each provided for a respective one of the plurality of pixels;a first set of lenses, each provided over a light receiving part of therespective one of the plurality of pixels and each being configured tocollect light onto the light receiving part; a second set of roundedlenses, each provided over one of the first set of lenses, and eachbeing configured to collect light onto the one of the first set oflenses; and a light blocker provided at a boundary between adjacentlenses of the first set of lenses and a light blocker provided at aboundary between adjacent lenses of the second set of rounded lenses,the light blocker being composed of a metal, wherein the light blockerprovided at the boundary between adjacent lenses of the first set oflenses is larger than the light blocker provided at the boundary betweenadjacent lenses of the second set of rounded lenses.